The field of the present invention is generally the design and construction industry and specifically precast concrete and structural steel construction systems.
The advantages of reinforced concrete have long been known in the building industry and reinforced concrete raised floors have been commonly used in buildings. But pouring the concrete on site, also known as casting in place, to create a structure is slow, labor intensive, and costly.
Construction projects using the cast-in-place technique for raised floors require extensive use of formwork, steel floor beam installation, galvanized metal deck installation, slab reinforcing installation, and the installation of slab embedded mechanical, electrical, IT, and plumbing items (MEP). All of this must be completed prior to casting the floor slab. This makes them heavier and costlier than the modular structural building system of the present invention. Additionally, the pouring, curing, and drying of concrete is weather dependent as time, moisture, and temperature play a part in the process and the quality.
In addition to the quality and time issues associated with the cast-in-place process, there are additional project schedule issues because, even once poured, it can be weeks before the concrete raised floor is in a condition to be walked on by the construction trades. Therefore, the construction of cast-in-place concrete raised floor slabs is always on the leading edge, or critical path, of the project schedule. Any time that can be gained through an early release of these raised floor slabs to trades will result in quicker project schedules, safer jobsites, and more cost-effective projects.
Rather than the cast-in-place process, precast concrete panels set in place and joined together on-site to create a raised floor have gained acceptance as a method to reduce time, labor, and material costs. Precast systems also provide a solution for remote jobsites that lack access to raw concrete. But current precast concrete floor panel systems have a variety of limitations and disadvantages. These floors are typically made of solid concrete and are thus much heavier than cast-in-place floors, which incorporate lighter steel components. The heaviness results in larger and more costly foundations and lateral systems. Further, precast raised floor slabs are usually simply installed side by side, often requiring the additional, cast-in-place pouring of a topping slab, which adds time and money to a project. A topping slab is also often required in precast raised floor systems in order to resist the seismic loads induced in moderate to severe earthquake exposure areas. But topping slabs can have their own surface defect issues depending on how they are poured. There can be additional camber, deflection, levelness, and flatness issues due in part to transitions across pre-cast floor panel connections.
Precast hollow core planks are also commonly used in the industry. These planks are extruded from dies and constructed of concrete material with continuous circular hollow openings the full length of the floor plank. These planks are reinforced with either conventional or prestressed reinforcing. Due to the extrusion process associated with hollow core planks, the final finish is rough and not aesthetically pleasing if left exposed and also may be difficult for floor finishes to adhere to properly. The top of hollow core slabs often has a dimple defect because as the concrete is extruded the top shell deflects downwards prior to the hardening of the concrete.
U.S. Pat. No. 8,499,511 to Platt, et al, discloses a precast composite floor system that combines the use of double tees and wide flange steel beams but does not have the advantages of the present invention, including levelling connection assemblies and the grout splicing method.
Also, U.S. Pat. No. 6,668,507 to Blanchet discloses a precast composite building system that combines the use of precast wall and floor panels and steel beams (primarily S-shaped), with welded joints between panels. This system does not have the benefits of the present invention such as the improved method of splicing adjacent floor panels, improved leveling connections, and it lacks the diaphragm chord reinforcement feature.
Thus, there is a need in the industry for a precast modular structural building system that addresses the limitations of the prior art. There is a further need in the industry to provide a modular building system with enhanced connection strength and levelling between composite raised floor panels. The present invention is designed to address these needs.